Treatment of hypertension produces major health benefits. It has been calculated that treatment with low-cost drugs is cost effective, and cost effectiveness increases with age. However, it is possible that the cost effectiveness of treatment has been calculated for the intervention group only. In addition, in many clinical trials, several patients in the control group use antihypertensive drugs, and some patients in the active treatment arm are not treated. Further, CEAs often do not account for all of the long-term effects of treatment such as decreased risk of heart failure and possible increase in risk of chronic diseases due to It is hypothesized that the treatment of isolated systolic hypertension in the elderly is cost effective when the long-term costs of care are analyzed. The primary specific aims of this amended grant application is to compare, during a mean follow-up of 4.5 years, the cumulative costs in the active treatment arm to the costs in the placebo arm of the Systolic Hypertension in the Elderly Program (SHEP). CEAs will be conducted from the societal perspective. The cost of care will be estimated by means of Medicare inpatient and outpatient claims for the SHEP participants and by calculating the treatment costs in both arms of the trial from randomization through the termination of the study or death. Disability adjusted life years (DALYs), quality adjusted life years (QALYs), and survival will be the outcomes for CEAs. Identifi-cation of cost-effective interventions is the first step towards efficient allocation of resources for preventing disabling illnesses in the older population.